Method for forming window envelopes or the like



Sept. 13, 1938.. R. L. GRAY METHOD FOR FORMING WINDOW ENVELOPES OR THE LIKE Filed June 14, 1935 4 Sheets-Sheet 1 BYW z A ATTORNEY.

'Sept. 13, 1938., R. L. GRAY 2,129,

- METHOD FOR FORMING WINDOW ENVELdPES'cSR" THE LIKE Filed June-14, 1953 Y 4 Shets-Sheet 2 INVENTOR.

faziikfl 6/647 -a ATTORNEY.

Sept. 13, 1938. R. GRAY Y 2,129,686

METHOD FOR FORMING WINDOW ENVELOPES OR THE LIKE Filed June 14, 1933 4 S'neets-Sheat 3 INVENTOR. Raga 271 6%45 ATTORNEY.

Spt.13,1938. R. 1.. GRAY 2,129,686

METHOD FOR FORMING WINDOW ENVELOPES OR THE'LIKE Filed June 14, 1933 4 Sheets-Sheet 4 Patented Sept. 13, 1938 UNiTED STATES METHOD roa FORMING wmnow EN- VELOPES on THE LIKE Robert L. Gray, Brooklyn, N. Y. Application June 14, 1933, Serial No. states 25 filaims.

This invention relates to a, method for forming window envelopes.

My invention is directed to the production of window envelopes of the so-called two piece type, in which the envelope body comprises a blank made of substantially opaque paper of any character, in which a cutout is formed on the face and a separately applied patch serves as a transparent closure for this cutout, through which an addressees name may be visible. The two piece type envelope may be generally referred to as "preferable to a one piece envelope in which transparency or transiucency is obtained at a window portion. ilhis translucency is obtained at any predetermined portion of the envelope by oiling or impregnating segregated portions of the envelope. This operation requires the choice of a particular type of paper to receive the impregnating material which renders the paper translucent. Such paper usually is oil thin and absorbent character, and of a texture sumciently fine to make the paper amenable to a saturating process. The requirement to use a paper having these absorbent characteristics not only. limits the choice of the paper but further requires that the non-translucent portionsbe further treated to make thesame more opaque.

In methods heretofore known to me for afixing a patch to an envelope blank in making a twopiece type of window envelope, the apparatus most emcient for this purpose utilizes a paper blank in which envelope forming flaps and sealing flaps are predetermlnedly defined thereon. The patch uniting operations usually include applying wet adhesive'to the body of the envelope blank surrounding the cutout, followed by an operation which contacts the patch to the envelope blank. Simultaneous with, or following this operation, the envelope forming flaps. are

folded into position over the portion forming the face of the envelope and that which carries the patch. The rapid succession of these steps, particularly that which involves the envelope forming step and the folding over of the envelope r forming flaps requires that special care be exercised to avoid the presence of any adhesive used in uniting the patch to the envelope blank beyond the confines of the patch. Otherwise, in the envelope forming steps simultaneous with or immediately following the pressing of the patch in position, this excess adhesive will unite the front and the back of the envelope to each other. This requirement, as well as the inability I to limit the adhesive to within the confines of the patch and the confines of. the cutout, has resulted in the adjustment of the apparatus for uniting the patch to the envelope blank by means which involve the application oi wet adhesive to the minimum area defined by the section of the patch which overlaps the cutout of the envelope. This has resulted in providing loose edges on the interior. of the envelope which interfere with the insertion of material therein and loose edges surrounding the cutout at the exterior of the envelope, which interfere in sorting or arranging the envelopes for mailing purposes, objectionable to the extent that the corner of one adjacent envelope may be snagged by these loose edges surrounding the cutout as well as providing a weakened union.

It is therefore an object of my invention to provide a method for making window envelopes of the so-called two piece type, which includes adhesively uniting a patch over a blank from which an envelope may be formed, utilizing adhesive extended over the contacting surfaces outlined by the portion at which the patch overlaps the cutout, to adhesively unite the peripheral portions of the patch which may interfere with filling of the envelope and/or the surface portions of the patch adjacent the peripheral edges of the cutout or adhesively uniting the parts at least co-extensive with a peripheral edgeot the patch at that edge which may interfere with the insertion of material in the completely formed envelope and/or co-extensive with the cutout defining the window, utilizing normally moist adhesive, and altering the character of the adhesive so that the envelope forming operations may immediately follow the patch uniting operations.

It is a further object of my invention to provide a method for forming a two piece type of window envelope in which apatch comprising substantially a transparency, is united to an envelope blank including a cutout by interposing a free flowing adhesive between the patch and the envelope and during the uniting oi the patch to the envelope blank, distributing the adhesive so that it is co -extensive with an edge of the patch which may interfere with the insertion of mate-' rial in the finally formed envelope and/or the cutout defining the window to avoid any loose edges at this point, and to render said adhesive so used inactive at any excess completing the envelope forming operations comprising folding envelope forming flaps over the face of the envelope carrying the adhesively united patch. 7

Still further objects of my invention reside in the provision of a method of forming a two piece type of window envelope which includes separately forming a patch formed of substantially transparent material and uniting the same to a sepa-' rately formed envelope blank, including a cutout, by interposing between the patch and the envelope blank a free flowing adhesive, the adhesive being supplied in a film in excess of the peripheral edges of the patch and/ or the cutout, followed by alteration of the adhesive to render the same inactive, and then followed by steps for the completion of the envelope forming operations to speedily-and economically complete the production of a two piece type envelope while producing an article which includes a peripheral edge thereof united to the envelope blank free from interference in inserting material into the completely formed envelope and/or in which the peripheral edges of the cutout are securely united to the patch, to avoid any objectionable loose edges at the exterior of the envelope.

Still further objects of my invention reside in the provision of a method for forming window envelopes comprising a separately formed, substantially transparent patch material and a separately formed envelope blank in which the patch is intimately united to the envelope blank over the cut out, and one or more peripheral edges of the patch are united to the blank and/or the peripheral edges of the cutout are united to the patch to form smooth and continuous edges, avoiding any interference in the use of the envelope in filling the same, or exteriorly thereof in handling the envelope.

To attain these objects and such further objects as appear herein or may hereinafter be pointed out, I make reference to the accompanying drawings, forming a part hereof, in which- Figure 1 is a fragmentary, longitudinal, sectional, diagrammatic view of my apparatus;

Figure 2 is a fragmentary sectional view showing the patch severing mechanism;

Figure 3 is an enlarged perspective view of an envelope blank and patch illustrating my method;

Figures 4 and 5 are enlarged fragmentary views illustrating the method at different stages;

Figures 6 and 7, respectively, are a plan view and a fragmentary plan view of an envelope blank forming another embodiment of my invention;

Figures 8 and 9 are fragmentary sectional views illustrating the successive stages of another embodiment of my invention;

Figure 10 is a fragmentary plan view of a window envelope as made by the embodiment illustrated in Figures 6, '7, 8 and 9;

Figures 11 and 12 are fragmentary sectional views illustrating another embodiment of my invention;

Figure 13 is a plan view of an envelope blank before union of the patch thereto in accordance with the method illustrated in Figures 11 and 12;

Figures 14, 15, 16 and 17 are diagrammatic views illustrating another embodiment of my invention, showing the progressive steps thereof;

Figure 18 is a diagrammatic plan view of apparatus for completing the patch uniting process;

Figure 19 is a section taken on the line l9--|9 of Figure 18.

For a clearer understanding of my invention, in my preferred practice in. the production of window envelopes, it is contemplated by me to utilize the features constituting the novel method and apparatus as part of envelope making machinery known on the market as either a two station or three station machine. This machinery blank ID in position.

is referred to merely for purposes of simplifying the consideration of this invention and it is not intended as a limitation upon the applicability thereof.

In envelope making machines of the character referred to as the three station machine, the following series of stepsis performed:a stack of envelope blanks l0, of the character illustrated in Figure 3, constituting a back fiap ll side flaps l2 and I3 and a sealing flap l4, formed at the face IS, with a cutout I6, is fed to a position where the back flap II and sealing fiap l4 have applied thereto thin applications of adhesive l7 and I 8, respectively. At this stage also, the existing methods include applying to sections surrounding the cutout IS, a thin film of adhesive. From this first station as described, the envelope blank is picked up and travels to the second station. At this second station, there is provided means for feeding a thin sheet of glassine paper or similar transparency. This sheet is fed to a suction plunger of predetermined configuration, depending upon the size of the patch to be applied. The plunger temporarily holds the patch and in its downward movement, presses against the envelope blank which has been moved immediately thereunder. As the plunger brings the patch in contact with the envelope blank immediately over the window cutout, the suction holding the patch to the plunger is released and the patch thereby transferred to the envelope blank. Following this operation, the blank now carrying the patch moves to a third station, wherein the envelope forming operations are performed and consist of folding the side flaps l2 and l3 and back flap l l overthe front face l5. Additionally, also, the sealing flap I4 is folded to lie closely over the envelope, the restriction being to avoid contact of the fresh adhesive l8 forming the seal with the remainder of the envelope.

In the two stage machine, the application of the adhesive to the back flap and sealing flap and adjacent the cutout is performed substantially the same as in the three stage machine. In the two stage machine, operations performed at stations numbered two and three in the machine first described, are performed substantially at one location or station, and to this extent differs from the three stage machine. Thus, at one location or station, the patch applying plunger continues in its movement and cooperates with other mechanism for folding the side flaps, back flap and sealing flap, substantially completing the envelope forming operations.

I will now describe such portion of my new apparatus which includes my new assembly and which is particularly applicable to the three-station machine for making window envelopes.

In Figure 1, the assembly illustrated is that which is disposed adjacent the second stage of the three-station machine, the variation being merely that in the first stage, the application of the adhesive surrounding the cutout may be omitted. In the apparatus illustrated in Figure 1, the blank I0 is brought in position upon a table IS, the face of which, 20, is provided with orifices 2| connected with a common chamber 22. This chamber is in turn connected with a pipe line 23 leading through a main suction chamber (not shown) and controlled by a valve 24. As the blank 10 is deposited upon the table I 9, coordinated mechanism controls the valve 24 so as to connect the suction line and thereby hold the The table I9 is provided with a central opening 25 and the positioning of phane (regenerated cellulose sheets) nitrocellu lose, acetyl cellulose or combined films thereof. Guide rolls 21 feed the strip through oppositely disposed rolls 28 and 29, adjacent which point a solution of adhesive is applied to the underface of the strip 26 for the full area thereof. The

' strip so treated is then fed to the plunger 30,

the face whereof, 3i, is provided with suction oriflees 32 connected with the chamber 33, operated by the suction line 34, and controlled by the valve 35. The valve 35 is so timed that upon leaving of the strip 26 from the rolls 28 and 29 respectively, the plunger will pick up asection or patch In the downward movement of the plunger, the latter cooperates with a knife 31 more clearly shown in Figure 2, to sever the patch 35 from the remainder of the strip, whereupon the remainder of the strip and knife 31 retract out of theposition to permit the plunger to continue its downward movement, carrying with it the patch 36 and the application or coating of the adhesive Site.

The plunger 30 is connected to the shaft 38 and is operated for reciprocation by the cam 39, which in turn is rotated by suitable driving means (not shown).

Surrounding the plunger 30 there is provided a heater housing it connected by a saddle M to a tubular shaft d2 concentric with the shaft 38, previously referred to. The shaft 52 is reciprocally operatedby the cam 3. The cams lid and it respectively, are so adjusted as to independently reciprocate the plunger 30 and the heater housing til and move the same over the table i9. However, they are timed so that the plunger leads the heater housing m in reaching the maximum downward displacement.

The plunger 30 carrying the patch 36 reaches the maximum displacement downwardly to intimately contact the patch. upon the envelope blank it. As care has been exercised to apply the adhesive 36a to the full peripheral edges of the patch, the pressure exerted by the plunger will displace some of the adhesive the interiorly of the cutout it, beyond the peripheral edges 36b to form fillets c and 36d, respectively, as will be more clearly apparent from an inspection of Figure 5. At this moment, the heater housing it is downwardly displaced adjacent the lowermost position of the plunger 33. This heater housing comprises a plurality of openings 63a connected with ducts 44 leading to a gas-line t5 and through the flexible tubing 46. The gas-line is controlled by the valve W to obtain the minimum amount of gas sufficient to provide a pilot light at the openings 43a in the uppermost position of the heater housing fill. As the heater housing descends to the position shown in dotted lines in Figure 1, the valve 41 is opened to the maximum position to increase the flame. The openings 53a are so adjusted to direct the flame towards the fillet 36d to instantly heat the same and dehydrate it at least partially to renderthe same adhesively inactive at their surfaces. The action is timed to be almost instantaneous and the amount of heat so projected upon the fillet 36d is insufiicient to in any way scorch or modify 7 49 are such as to direct heat in the form of jets of flame, or similarly effective means towards the edge of the c'utout l6 to reach the fillet 360 which may have been formed.' The supply of gas to the heater 48 is controlled by the line 50 also controlled by the valve 41 previously referred to, and is such that when the plunger 30 is in the upper position, a pilot light is maintained at the orifice 49. However, immediately following the application of pressure by the plunger 30, and at the point where the adhesive 36a is extruded into the cutout Hi, the flame through the orifice 49 is increased for a short periodto also eifect the dehydrating action upon the fillet 36c. It will be understood that though I have described and illustrated the use of gas heat for accomplishing the dehydrating action, other means may be utilized such as radiant heat, a blast of air which may also be he'ated,'or similar or other equivalent dehydrating means. The series of steps just described serve to unite the patch 36 to the blank ill at substantially the entire contacting area of the patch and blank, uniting the peripheral edges of the patch, as well as uniting the patch to the peripheral edges of the cutout. The extruded adhesive 36c and 38d serves to provide a continuous surface both to the interior and exterior of the envelope formed in the subsequent. operations. Upon union of the patch and the envelope bianlr as just described and by the dehydrating action to which the adhesive has been subjected, the'blank carrying the patch may then pass to the third stage of the envelope forming process. Here, the side flaps are first folded down over the face it of the envelope and the back flap ii contacted therewith to hold the same in position by the uniting action of the film of adhesive it. This substantially comprises the main stages of the envelope forming operations and'rnay immediately follow the patch applying operation of the dehydrating step previously described, be accomplished without uniting the front face and the rear face of the envelope to each other.

In such phases of my process as just described, wherein the patch St is given a continuous coat ing Sta of adhesive material which may be exposed through the cutout it of l the envelope blank it, this will also be subjected to a certain amount of dehydrating action by reason of the position of the heater it, as previously described. For further assuring the presentation of a surface which does not become tacky when handled, it is preferred by me to include in the adhesive used, ingredients which have an insolubilizing action upon the glue, where this is used as the adhesive. Thus, in the preparation of the adheslve used by the applicator roll 29, quantities of formaldehyde, potassium chromate or similar ingredients which insolubilize glue, or render the same less tacky to the touch may be-added to the'glue solutions used.

In the embodiment just described, the adhesive necessary for uniting the patch to the envelope blank is interposed between the patch and the adhesive blank by applying the same to the transparent patch.

In another embodiment of my invention as specifically illustratedin Figures 6 to 10, the operations may be changed so as to first apply the adhesive to the envelope blank and leave the transparent patch untreated. Referring to Figures 6 to 10, it will be observed that in these just described. The contacting of any portions of the side flaps and back iiaps over the patch 'on the interior of the envelope may, as a result embodiments of my invention, the blank l may be treated at the first stage so as to apply to the back flap 'l l, the film of adhesive l1, and to the sealing flap H, the film of adhesive 18. At this application, applicator rolls may be provided to apply to the face I 5 immediately surrounding the cutout 16, a film of adhesive 36a. The outline of this film of adhesive is calculated to be in excess to be substantially the same or greater than the area of the patch.

While it is preferred to attempt to obtainregistry of the outline 366 with that of the patch 36, the operation otherwise is substantially the same as that previously described in the embodiment illustrated in Figures 4 and 5. The patch 36 is pressed into engagement with the envelope blank I0 carrying in this embodiment, the film of adhesive 36a. The pressure of uniting the patch to the blank III will serve to extrude a portion of the free adhesive beyond the periphery of the patch and to within the cutout l6 of the envelope blank forming fillets within the periphery of the patch and adjacent the'edg'e of the cutout l6. Surface or complete dehydration of these fillets or any other excess adhesive, may be accomplished by suitable dehydrating means as in accordance with the apparatus previously referred to and described in connection with Figure 1.

It will be understood that in illustrating this construction and the showing of the fillets, these are greatly exaggerated for purposes of more clearly illustrating the invention, but in actual size, they are very minute and will in no way interfere with the appearance or flexibility of the product. It will alsobe understood that while the I gum material used in any of the preceding embodiments, whether this gum is applied to the surface of the transparent patch or to the surface of the envelope blank, is of the character which is active in the presence of moisture, upon dehydration it will exhibit properties inactive to the touch or the natural moisture of the fingers in handling the same. This I may accomplish by proper alternation of the constituents of the gum. I may augment this inactive property in the finally dehydrated stage by including in the moistening fluid an insolubilizing agent, such as aldehyde products, formaldehyde, acids, such as chromic acid or potassium chromate compounds.

While I'have described in connection with the embodiments illustrated in Figures 1-5, the use of a strip of transparency to which, just prior to union of the patch to the envelope blank there may be applied a coating of adhesive material for the complete'area of the transparency, the applicator for this purpose may be one which limits the application of the adhesive to the area substantially adjacent the periphery of the patch, excluding any application of adhesive to the patch which eventually overlies the cutout. While I may start with a transparent strip which has no coating, the same being fed to the apparatus from a continuous roll and severed at the time of application, I may use a strip of transparency supplied as a continuous sheet in a roll, which has a normally dry coating of adhesive material which is heat plastic or may be activated to ad: hesiveness by the use of a solvent. Such material as I may use is referred to in my prior filed application, S. N. 565,038. Thus, the transparency may be glassine paper of a high state of translucency, approaching transparency, having a gum coating or a coating of nitrocellulose or a transparent film of regenerated cellulose, such as Cellophane, having a coating of gums or resins.

In this embodiment of my invention, the transparency carrying the normally dry adhesive coating is positioned over the envelope blank, which blank has first been treated with a solvent for the adhesive coating, and the union of the patch to the envelope blank over the cutout is effected by heat and pressure in the presence of the solvent for the adhesive coating. To assure the presence of suflicient solvent material, the application of the solvent is preferably in the form of a paste or gelatinous mass, the gelatinous mass being of fugitive character. The ingredient which gives the solvent the pasty characteristic is present in such minute quantities as to add substantially no objectionable properties to the interior of the envelope when it has dried.

For a clearer understanding of this embodiment of my invention, reference will now be made to Figures 11-13. In this embodiment, there is provided a sheet of transparent or translucent material, such as glassine paper, carrying normally dry transparent adhesive or waterproofing coating of the character referred to in my prior application and hereinabove briefly mentioned and preferably said coating being on one side only of said transparent or translucent sheet. The apparatus which may be used may include the heated plunger in accordance with my aforementioned application. An envelope blank I0 is moved into position upon the apparatus to a point where an applicator provides a coating 36f of a paste comprising a solvent. This paste coating is applied over the surface l5 of the envelope blank surrounding the cutout IG, for an area substantially greater than that covered by the patch 36 carrying the normally dry adhesive coating. At this stage of the operation, the patch is pressed into contacting position with the envelope blank while heat is applied. With an extremely active solvent forming the coating 36 pressure alone may be used, though the combinatioh of .heat and pressure is preferred. Otherwise, in all respects, this procedure is similar to the procedure outlined in my co-pending application aforementioned.

' The application of heat and pressure serves not only to activate the adhesive coating to plasticity but the paste coating 36/ further activates the same, and with greater speed of reaction. The presence of the heat disseminates the adhesive into the paper and merges the contacting edges into an extremely intimate bond or weld. This variation permits of higher speeds of operation in applying the patch and the time element necessary for pressing the patch into position may be reduced to the minimum.

The effect of the heat will also serve to diffuse the solvent constitutent in the paste, leaving a residuum too minute'in quantity to be observable or objectionable.

Where I use a sheet of transparency having a glue or gum adhesive coating of normally dry character, the paste coating 36f is made from a paste obtained by whipping small quantities of soap and water, and using the thick lather so produced. Where the transparency carries an adhesive or waterproof coating which is soluble in organic solvents, the solvent medium may be acetone, ethyl acetate, amyl acetate, mixedsolvents of high boiling and low boiling characteristics, depending upon the nature and character of the waterproofing coating. Where nitrocellulose is used as the waterproofing coating or as an ingredient of the waterproofing coating 01 the transparency, such as glassine paper, coated on one side with a nitro-cellulose base material, the solvent may be ethyl or amyl acetate or the Ceilosolve solvents, such as ethylene glycol monoethyl ether, ethylene glycol mono-methyl ether mono acetate (methyl Cellosolve acetate) or ethylene glycol mono-methyl ether (methyl Cellosolve). The ethylene glycol acetates may also be used. The solvents may be formed into a paste or lather with dificultly soluble gelatinized nitro-cellulose or soaps, or such materials comprising minute quantities of gel or body imparting materials so that the activator maybe applied as a smear. Such preparations are similar to a 'gell, plastic or semi-solid fuels, of which Sterno is an example.

One essential characteristic of the waterproofing coating activating paste in the nature oi solidified fuels is that it has an organic solvent as its principal constituent, which solvent rapidly activates to adhesiveness the waterproofing coating. A certain degree of tackiness of temporary character sufiicient to assist in transferring the patch from the plunger .carrying it and also to retard the volatilization of the solvent, is another desirablecharacteristic. A wetting action of the paste or solvent of the'paper and a merging of the waterproofing adhesive on the transparency with the paper under the heat of the plunger to reduce the time of the uniting operation as well as the intimacy of the bond is also another essential characteristic.

While I prefer to apply the coating at]? in the form of a paste in that greater quantities of this material may be added and the film thereof persist for a sufficient period of time to activate the normally dry adhesive coating of the transparency, when this comes in contact therewith, it will be understood that the coating 3t may be the solvent itself, but this is not as desirable.

In choosing the solvent or the solvent paste which is to be applied as the coating lit attention is to be given to the nature of the paper forming the envelope iii and the sizing carried thereby so as not to alter the same by reason of its use, and an intimate knowledge or the nature of the paper used, to take these rectors into account, is desirable.

At this point, it may be noted that the procedure described immediately above may include, as part of the activating solvent, a film forming material, such as nitro-cellulose and a plasticizer or cellulose acetate and a plasticizer, and is applied in suitable solvents which are also activating materials for the normally dry adhesive coatings, covering the transparency. These fllm forming materials are not active adhesives for the paper itself except under the action of heat, which serves to disperse the film forming material into the pores of the paper. 'Whenthe pressure is applied to the patch by the plunger in the presence ofheat, the action is to activate the adhesive coating on the patch and merge the patch and the paper, and to cause the film forming material carriedby the film 38! to dry beyond the peripheries of the patch. The resultant film, whether dry or wet,.as a result of this action will not serve to unite the envelope forming flaps to the body of the envelope by succeeding steps which comprise the envelope forming operations.

I may, at the same time that the film 36! is applied, also include with the solvent and film forming material, a pigmenting material, and at the time that this film is applied to the envelope blank, coat substantially the entire area of the envelope and envelope forming flaps on the portion constituting the interior or the envelope. Where such operations are employed, the film forming material and pigmenting material may outline some ornamentation, thereby serving to opacity the envelope blank paper, permitting the use of a thinner grade of paper.

Under such mode of operatiomthe applicator for the film til where it is distributed over the entire areaoi the envelope or the envelope forming flaps, may constitute a printing roller which outlines some form of pleasing ornamentation.

I may also, by this mode of operation, utilize paper for the envelope blank which carries an ornamentation of some desirable character and which may be applied to the paper before the envelope blanks are stamped therefrom. The film.

forming material carrying the pigmenting material not only serves to ornament the paper and opacify the same, but also is of a character which is activatable to adhesiveness by heat.

Under such conditions of operation, in applying the patch by a heated plunger accompanied by pressure, the heat serves to activate the film carried by the patch and the film of ornamentation carried by the paper or either one of them, to unite the patch to the envelopeblanlz. It will also be observed that under such conditions of operation, the heat activatable film on the patch may be omitted, provided the film. forming material serving as an opacifier for the paper, carries hit that on the patch orthat due to the film on either of these materials, where the coating is applied only to one of these elements, under which latter conditions, it is preferred to use a solvent or paste solvent activator. l

In a still further embodiment of my invention, I may combine the existing methods heretofore described with that of my companion application aforementioned, to the extent that the patch used for the transparency and covering the cutout of the envelope blanl:,'is a material described in my co-pending application, Serial No. 565,038, comprising a transparency which carries an adhesive coating of normally dry characteristics, which may be activated to adhesiveness by fusion under heat. Such material may be utilized with existing methods to the extent that this patch is located with wet adhesive over the cutout, merely using the minimum amount of adhesive necessary for so locating the patch. The envelope blank and the patch carried thereby then pass through 'the' envelope finishing operations in which the hesive 36g is applied, as shown in Figure 15.

Following this operation, there is superimposed a patch 36, carrying on the surface directed to the envelope blank, a film of normally dry adhesive material which may be activated to adhesiveness by heat. This patch is applied while. the spotting of the adhesive 369 is still moist. The blank then passes through the envelope forming operations wherein the back flap H and side flaps I2 and I3 are folded in position to complete the formation of the envelope, as illustrated in Figure 17. The envelope as thus prepared'is then submitted to heat and pressure on the back and front face, preferably by. passing the same through rollers 6| and 62, having at their interior heating elements 63, connected to some electrical source 64 by commutators 65. The rollers serve to intimately press-the patch into position, sufficient heat being utilized to fuse the adhesive coating carried thereby. Heat and pressure appliances of the character described and illustrated in my prior filed application, aforementioned, may be used instead of the rollers. By this embodiment, existing apparatus may be utilized and greater speed of production obtained in that the patch locating process occupies the minimum period of time and further does not require any specific coordination between the wet application of the adhesive to the cutout and to the patch used, as the function of the wet adhesive is primarily to locate the patch and not to serve as a means for uniting the patch to the envelope blank. This method is further desirable, so far as weld-- ing the patch in position is concerned, in that the heat and pressure that is used may be more readily accommodated to a larger variety of heat fusible adhesives carried by the patch, thereby avoiding the exercise of undue care and attention in the choice of the fusible adhesive film which may be used for the transparency.

It will be observed that by the method and apparatus described, window envelopes of the two-piece typ can be made economically, with a high order of speed of production, to result in a product in which the patch covering the window cutout is intimately connected to the body of the blank, without the formation of loose edges either interiorly or exteriorly thereof. It will also be observed that though it is preferred by me, by the processes heretofore described, to unite substantially the entire patch to the envelope blank, to accomplish the desirable properties heretofore mentioned, it is sufficient for my purposes to unite the patch to the edges of the cutout, without any loose edges, and/or to unite a peripheral edge of the patch on such portions directed towards the filling side of the envelope so that no loose edges are provided which may interfere with the insertion of material into the envelope, and that other edges remote from the filling side of the envelope may, therefore, be left free. This latter mode of operation permits one machine to take care of various sizes of envelopes and various sizes of patches, and the relative positioning of the cutout in respect to the patch applying mechanism.

overlaying the patch over the cutout, interposing a normally fluid adhesive film for an area at least as great as the size of the patch, pressing the patch in position upon the envelope blank whereby an excess may be formed beyond the periphery of the patch or within the confines of the cutout, rendering the excess adhesive inactive before performing the envelope forming operations, and then folding the flaps into envelope forming position.

2. The method of forming window envelopes from an envelope forming blank including a cutout and a separately formed patch comprising substantially transparent sheeting, the steps which include overlaying the patch over the cutout, including a fluid adhesive coating interposed between the patch and the envelope blank, the fluid coating being distributed for an area corresponding to portions adjacent the peripheral edges of the cutout and portions adjacent the peripheral edges of the patch, pressing the patch in position so that extraneous adhesive is pressed beyond a peripheral edge of the patch adjacent the filling side of the envelope and beyond the peripheral edges of the cutout, dehydratingthe extraneous adhesive on the interior of the envelope and then completing the envelope forming operations.

3. The method of forming window envelopes from an envelope forming blank including a cutout adapted to form a window portion and a separately formed patch comprising a substantially transparent sheeting, the steps which comprise overlapping the transparencympon one face of the blank over the cutout, interposing a fluid adhesive material for substantially the full area of the overlap to form an excess at the peripheral portion of the patch and the peripheral portion of the cutout and subjecting the excess adhesive at the peripheral portions of the patch to dehydrating conditions and immediately completing the envelope forming operations.

4. The method of forming window envelopes from an envelope forming blank including a cutout for providing a window portion and a separately formed patch comprising a substantially transparent sheeting, the steps which comprise overlaying the patch over the cutout, interposing a normally fluid adhesive coating between the patch and the blank, pressing the patch in position and extruding an excess portion of the adhesive at a peripheral portion of the patchadjacent the window envelope, to completely seal said peripheral edge without the formation of loose edges, subjecting said excess adhesive to dehydrating conditions to render said excess adhesive inactive and then completing the envelope 1 forming operations by folding the envelope forming flaps over the body of the envelope to which the patch has been applied.

5. The method of forming window envelopes from dissimilar materials comprising substantially opaque paper and a'substantially transparent sheeting adapted to form the window portion, the steps which comprise overlapping the transparent sheeting over a portion of the opaque paper, thereby forming an overlapping joint, interposing a normally fluid adhesive between said overlapping Joint and then pressing the transparent sheetinginto engagement with the paper, providing an excess adjacent the periphery of the transparent sheeting and the paper of the overlapping joint, rapidly dehydrating a surface portion of the excess adhesive thus formed to ren- 5 material carrying a substantially complete coat-' der the same inactive and then completely performing the envelope forming operations.

6. The method of forming window envelopes from an envelope forming blank including a cutout and a separately formed patch comprising a substantially transparent sheeting, the steps which comprise overlaying the patch over the cutout including a substantially fluid adhesive coating interposed between-the patch and the envelope blank, the fluid adhesive being distributed for an area comprising the contacting portions of the patch and the envelope blank, pressing the patch into position providing an excess at the peripheral portion of the patch and the peripheral portions of the cutout, simulta neously subjecting the excess portions to dehydrating conditions, rendering the surface portion of the excess adhesive inactive, and thereafter completing the envelopeiorming operations.

7. The method of forming window envelopes from an envelope forming blank including a cutout and a separately formed patch comprising a substantially transparent sheeting, the steps which include overlaying a patchof transparent ing of a fluid adhesive over the cutout, pressing the patch over the cutout to contact the adhesive with the envelope blank to provide an excess adhesive material at the peripheral portions, of the patch and the cutout, rendering the excess adhesive adjacent the periphery of the patch inactive, and then completely performing the envelope forming operations.

'8. The method of forming window envelopes 35 from an envelope forming blank including a cutout and a separately formed patch comprising a substantially transparent sheeting, the steps which include applying a normally fluid adhesive to the envelope blank surrounding the cutout for an area corresponding substantially to the patch, pressing the patch in position in contact with the adhesive coating thus provided under pressure displacing an excess of the adhesive beyond the periphery of the patch or within the confines oi the cut-out, rendering the excess adhesive inactive and then completely performing the envelope forming operations.

'9. The method of forming window envelopes from an envelope forming blank including a cut= out and a separately formed patch comprising a substantially transparent sheeting, the steps which include overlaying the patch over the cutout of the blank by a normally fluid adhesive, providing a substantially continuous adhesive coating between the patch and the envelope blank incompletely uniting the patch to the blank to thereby locate the patch, and then completely uniting'the patch to the envelope blank at portions-at which the patch overlaps the cutout.

10. The method of forming window envelopes from an envelope forming blank including a cutout and a separately formed patch comprising a substantially transparent sheeting, the steps which include overlaying a patch including an 5 adhesive coating interposed between the patch 70 uniting the patch to the envelope blank at a. pc-

arid the envelope blank for substantially the complete area of the patch, adhesively contacting the patch tothe envelope blank, completely performing the envelope forming operations and then 75 out and a separately formed patch comprising a.

substantially transparent sheeting, the steps which include overlaying a patch including an adhesive coating interposed between the patch and the envelope blank for substantially the complete area oi the patch, adhesively contacting the patch to the envelope blank, completely perform- ,ing the envelope forming operations and then uniting the patch to the envelope blank at a peripheral portion of the filling side of the envelope and at a peripheral portion of the cutout.

12. The method of forming window envelopes comprising a body portion of substantially opaque paper including a cutout and a separately formed sheeting of transparent material comprising the patch, the steps which comprise providing said transparent material with a normally dry adhesive coating, applying to at least one of the elements comprising the body portion and patch a. solvent for the adhesive to render the same active overlapping said patch in position over the cutout, and pressing said patch into contacting.

position with said envelope blank.

13. The method of forming window envelopes comprising a body portion of substantially opaque paper including a cutout and a separately formed sheeting of transparent material comprising a patch, the steps which comprise providing said of the character described, including a blank formed with a cutout, the steps which comprise uniting a patch formed of substantially transparent material over said cutout, said patch forming material having a waterproof adhesive coating, applying to at least one of the elements comprising the blank and patch a fluid capable of activating said coating to adhesiveness overlaying said patch over the cutout and uniting the patch to the paper under pressure.

15. The method oi forming a paper container of the character described, including a blank formed with a. cutout, the steps which comprise uniting a patch formed of substantially transparent material over said cutout, said patch forming material having a waterproof adhesive surface material, applying to at least one of said elements comprising the blank and patch, a fluid capable of activating said surface material to adhesiveness, overlaying said patch over the cutout and uniting the patch to the paper under pressure while applying heat thereto thereby uniting the patch to the blank.

16. The method of forming an article of the character described including a container body formed of paper and formed with a cutout, uniting a patch or a substantially transparent sheeting over said cutout, said transparent sheeting including a solvent and heat activatable surface coating material, applying a film including a solvent upon the paper blank surrounding the cutout and pressing said patch in position to activate the coating on said transparent sheeting and adhesively unite said patch to the paper.

17. The method of forming an article of the character described including a container body formed of paper and formed with a cutout, uniting a patch of a substantially transparent sheetlid ing over said cutout, said transparent sheeting including a solvent and heat activatable surface coating material, applying a film including a solvent upon the paper blank surrounding the cutout and pressing said patch in position to activate the coating on said transparent sheeting and adhesively unite said patch to the paper, said solvent being combined with a film forming material of itself inactive to paper when dry.

18. The method of forming a window container of the character described comprising providing a paper blank including a cutout, a substantially transparent sheeting serving to overlap said cut out, said sheeting including a heat and solvent activatable coating, distributing a film including a solvent for the coating of the patch from the periphery of the cutout to an area greater than the patch and then pressing said patch into position while applying heat thereto, to merge the' coating of said patch with the paper of at least the area of such patch extending to a periphery thereof directed towards the filling side of the container.

19. The method of forming a container of the character described from a paper blank including.

a cutout, uniting a sheet of substantially transparent material over said cutout by overlapping said sheeting over said cutout, the steps which include providing said sheeting with a continuous waterproof coating of solvent activatable material,- distributing around the cutout a film forming material of tacky characteristics, in-' cluding a solvent, pressing the patch into position over said cutout to cause activation of the waterproof coating and applying heat to said patch to disperse the solvent and unite the patch to the paper.

20. A method of forming a window container of the character described comprising a paper blank including a cutout, the steps which include providing a patch of substantially transparent material including a solvent activatable coating, distributing a film of solvent over the paper blank from adjacent the periphery of the cutout foran area greater than the outline of the patch, overlaying said patch over the film thusformed to activate the adhesive coating on said patch, and pressing said patch in position to uniformly unite the patch to the paper.

21. A method of forming a window container of the character described comprising a paper blank including a cutout, the steps which include providing a patch of substantially transparent material including a solvent activatable coating,

to activate the adhesive coating on said patch, and pressing said patch in position adjacent the periphery of the cutout and a peripheral portion of the patch adjacent the filling side of the container to unite said patch to the paper blank.

22. In the manufacture of window envelopes, the method of applying a translucent patch to the envelope blank containing the window which consists in applying an adhesive solvent to one of the members comprising patch and blank so as to include the area to be united, then while the solvent treated member is still wet, bringing the other member previously treated with the adhesive and in a substantially dry state and said solvent treated member together in proper registry, thereby causing said members to be united.

.23. In the manufacture of window envelopes, the method of applying a translucent patch to the envelope blank containing a window which consists in applying an adhesive solvent to the envelope blank around the window so as to include the area of the envelope surface to be covered by the patch, then while the solvent is still wet, applying in proper registry .the patch, which previously has been adhesively coated to substantially the edge and allowed to become sub stantially dry, to said blank thereby causing the patch and blank to unite.

24. In the manufacture of window envelopes, the method of applying a translucent patch to the envelope blank containing a window which consists'in applying an adhesive solvent to one of the members comprising patch and blank so as to include the area to be united, then while the solvent treated member is still wet bringing the other member previously treated with adhesive in a substantially dry state and said solvent treated member together in proper registry thereby causing said members to be united, the patch member being treated with the adhesive element at least to the extreme edge which is to be adjacent the fold line of the sealing flap whereby the patch is secured to said extreme edge.

25. In the manufacture of window envelopes, the method of applying a translucent patch to the envelope blank containing a window, which consists in applying an adhesive solvent to one of the members comprising patch and blank over an area somewhat greater than the area to be united and inclusive of 'such area, then while the solvent treated member is still wet, bringing the other member previously treated with adhesive and in a substantially dry state and said solvent treated member together in proper registry thereby causing said members to be united.

ROBT. L. GRAY. 

